
use std::error::Error;
use std::fs;

pub struct Config {
    pub query: String,
    pub file_path: String,
}

impl Config {
    // 解析参数
    pub fn parse_params(args: &[String]) -> Result<Config, &'static str> {
        if args.len() < 3 {
            return Err("not enough arguments");
        }
        let query = args[1].clone();
        let file_path = args[2].clone();
        Ok(Config { query, file_path })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.file_path)?;
    if let Some(index) = contents.find(config.query.as_str()) {
        println!("The substring '{}' starts at index {}", config.query, index);
    } else {
        println!("Substring not found.");
    }
    Ok(())
}
